Facile Fabrication of Composite Vanadium Oxide Thin Films with Enhanced Thermochromic Properties

Abstract

In general, high-purity monoclinic VO 2 (VO 2 (M)) was considered as a prerequisite for obtaining VO 2 -based thermochromic coatings with high performance. The coexistence of other vanadium oxides (such as V 3 O 7 and V 2 O 5 ) in VO 2 coatings was regarded as an unfavorable issue. Here, we investigate the microstructures and thermochromic properties of the composite vanadium oxide (CVO) thin films. The results demonstrate that the proper coexistence of high valent vanadium oxides (V 3 O 7 and V 2 O 5 ) in VO 2based films can remarkably enhance the thermochromic performance of films. The CVO thin films were prepared by a room-temperature sputtering process followed by a modified rapid annealing routine in air. The structural analyses (X-ray diffraction, Raman spectroscopy, and transmission electron microscopy) reveal the coexistence of VO 2 (M), V 3 O 7 (M), and V 2 O 5 (O) in CVO thin films. The luminous transmittance (T lum ) and solar modulation ability (ΔT sol ) of the CVO thin film obtained by an optimal preparation process are 1.93 and 1.34 times those of the pure polycrystalline VO 2 thin film, respectively. Moreover, the CVO thin film exhibits lower semiconductorto-metal transition temperature (60.8 °C) than the pure VO 2 (M) thin film (67.9 °C). Furthermore, the fabrication process is well-reproducible, which is highly attractive for the mass production.

Scandium: An efficient dopant to modulate the optical spectrum of vanadium dioxide (VO2)

“…This is attributed to reduction in -angle [31]. (b) The reduced transmission in visible range after coating VO 2 on the glass resists its use as a smart window material [27,32]. The dopants added either reduce the T SMT or manipulate the optical spectrum.…”

Phase Transition Hysteresis of Tungsten Doped VO2 Synergistically Boosts the Function of Smart Windows in Ambient Conditions

“…%. As shown in Figure c, the W3 film with balanced optical properties ( T lum = 50.8%, Δ T sol = 11.4%) exhibited better energy-saving performance than the 2D-patterned VO 2 film ( T lum = 46.1%, Δ T sol = 13.2%), composite vanadium oxide thin film ( T lum = 28%, Δ T sol = 19.4%), VO 2 film synthesized from the inkjet printing method ( T lum = 40.0%, Δ T sol = 9.7%), and large-scale VO 2 film from high-throughput roll-to-roll fabrication ( T lum = 41.4%, Δ T sol = 7.1%) . Our results are comparable to those of the Sn-doped VO 2 film ( T lum = 51.8%, Δ T sol = 15.4%) obtained from the hydrothermal process and Fe/Mg co-doped VO 2 film ( T lum = 45.2%, Δ T sol = 12.8%) synthesized by DC reactive magnetron sputtering.…”

“…(b) T lum and Δ T sol as a function of W content of VO 2 . (c) T lum and Δ T sol of different VO 2 films with reported T c values in parentheses: pristine VO 2 films including the 2D-patterned VO 2 film, composite VO x film, inkjet printing, and roll to roll and doped VO 2 films such as Sn-doped, Mg-doped, W doped, and Fe/Mg co-doped VO 2 films. (d) The T 1200 –temperature hysteresis loops of W-doped VO 2 films.…”

Effect of Mie Scattering on Thermochromic Performance of Branched VO2 Prepared by One‐Step Hydrothermal Method

“…The preparing of stoichiometric VO 2 faces a perennial challenge because the rich valence of vanadium element usually leads to the formation of other competing vanadium oxides in VO 2 . Furthermore, VO 2 can adopt at least ten kinds of polymorphs, including VO 2 (A), VO 2 (B), VO 2 (M/R), VO 2 (D), VO 2 (P), and so on. Surely, the structural diversity expands the potential applications of VO 2 polymorphs ranging from field‐emission devices, sensors, electrochemical energy strorage .…”